ABSTRACT
A film of [Pd(R2pipdt)(dmit)] (1), where R2pipdt = 1,4-didodecyl-piperazine-2,3-dithione (acceptor) and dmit = 2-thioxo-1,3-dithiole-4,5-dithiolate (donor) incorporated into a polymethylmethacrylate (PMMA) matrix, showing a good second-harmonic generation, has been prepared for the first time in the class of dithione-dithiolate 2nd order NLO-chromophores. Moreover full characterization of 1, including molecular second-order NLO properties in solution, is reported.
ABSTRACT
We report the synthesis, structure, and physical properties of (BEDT-TTF)[Ni(tdas)2] [BEDT-TTF, or ET, is bis(ethylenedithio)tetrathiafulvalene; tdas is 1,2,5-thiadiazole-3,4-dithiolate], which is the first example of a salt containing monomeric [Ni(tdas)2]- monoanions. This salt, which crystallizes in the monoclinic space group P2(1)/c with a = 17.2324(6) A, b = 13.2740(5) A, c = 10.9467(4) A, beta = 96.974(2) degrees, and V = 2485.5(2) A(3), forms a layered structure. One layer contains dimerized BEDT-TTF electron donor molecules and isolated [Ni(tdas)2]- monoanions, while the second layer contains chains of [Ni(tdas)2]- monoanions. Conductivity measurements show that (BEDT-TTF)[Ni(tdas)2] has a semiconductor-to-semiconductor transition near 200 K, while magnetic measurements indicate that it is an S = 1/2 paramagnet with weak antiferromagnetic coupling. Reflectance spectra reveal bands in the near-infrared region (6.6 x 10(3) and 10.6 x 10(3) cm(-1)) which are typical of (BEDT-TTF)2(2+) dimers. From these data, we can conclude that the unpaired electron lies on the [Ni(tdas)2]- anions. Tight-binding band structure calculations were used to analyze the electronic structure of this salt.
ABSTRACT
A simple method to obtain in high yields mixed-ligand nickel-dithiolene complexes, which show strong negative solvatochromism and negative first molecular hyperpolarizability, and the use of Raman spectroscopy to establish the extent of electronic delocalisation in these complexes, are reported.
ABSTRACT
A series of derivatives belonging to a new class of compounds (R4-todit) were highly cytotoxic to a panel of leukaemia- and solid tumour-derived cell lines (IC50 = 0.06-20 microM). The most potent compound was the butyl4 derivative (IC50 = 0.06-5.1 microM); T leukaemia and melanoma cells were the most susceptible cells to this inhibitor (IC50 0.06 microM and 0.1 microM, respectively). The effect of butyl4-todit was irreversible, and led to progressive cell death. The compound showed a comparable potency against exponentially growing and stationary phase cells, and against cell lines expressing the MDR phenotype. The cytotoxicity of butyl4-todit in human normal PBL was up to 20 fold lower than that shown against T leukaemia cells. When tested for antiangiogenic activity in vivo, 1.5 mg/Kg butyl4-todit resulted in over 70% inhibition of the angiogenesis process induced in mice by Kaposi's sarcoma cell secreted products.
